Electronic units and method for packaging and assembly of said electronic units

ABSTRACT

The present invention discloses method for packaging and assembly of electronic units comprising a multi-planar board system in which each single planar board provides electrical contacts and/or signal drive to its successive planar board via a flexible cable forming the only connection between successive planar boards. In its packaged position the planar boards are laid upon one another without affixing them with each other or affixing them with the housing of the electronic unit, wherein the packaging of the planar boards preferably forming a daisy chain. Positioning and adjusting of the planar boards to each other is mainly achieved by the cover element being wrapped around all surfaces of the planar boards during the packaging process, positioning and clamping of the packaging of the planar boards within the housing is mainly achieved by the self-adapting suspension during the assembly process of the electronic unit into the housing. The cover element separating and concurrently adjusting each planar boards to each other has isolating, stabilizing, heat draining, and flexible attributes. The electronic unit is preferably arranged in a screw-less, and scalable housing.

BACKGROUND OF THE INVENTION

[0001] 1) Field of the Invention

[0002] The present invention relates to a method for packaging andassembly of electronic units and more particularly to packaging andassembly of electronic units requiring mechanical robustness and beingused in rugged environmental conditions such as e.g. demanded byelectronic devices used in industrial machinery and automotive controlunits.

[0003] 2) Prior Art

[0004] Electronic units as addressed by the present invention arepreferably small scalable electronic devices or embedded electronicdevices, e.g. handheld devices, set-top systems, internet appliances,mainly used in rugged environmental conditions such as e.g. demanded byelectronic devices used in industrial machinery tools and automotiveelectronic units. They normally comprising at least a processor, astorage media (ROM, RAM), and interfaces, e.g. interfaces to user and/orcomponents to be controlled. The electronic unit itself is mostlyarranged in a housing. The electronic components being part of theelectronic units may be arranged in the housing either in acard-on-board system or a card stack system.

[0005] Typically card-on-board systems utilize a base planar-board(mother board) featuring extension slots and connectors allowing tocustomize/scale the system by adding on various system feature cards.The minimum base system is providing the overhead on power-source signaldrive capability and electrical connectors supporting to assemble systemconfiguration. As a result, it is necessary that the electroniccomponents positioning within the housing of the electronic units bemaintained. In addition, many card-on-board systems are developed tosatisfy the requirements of a particular electronic assembly. Therefore,as the system size and configuration changes, an additional package isrequired which would also require changes on the mother-board. As aresult, packaging for electronic units is relatively expensive.

[0006] Card stack systems provide a multi-planar-board system. The basicsystem functions as well as the potential system expansions aresub-divided and implemented into individual single planar boards. Thesingle boards are rigidly stacked in a housing and separated by spacers.Electrical contacts and the signal drive between the single planarboards are achieved via specifically designed connectors. Finally, themulti-planar board system is separated from the housing of theelectronic unit by a shock absorbing arrangement. The prior art cardstack system does provide scalable electronic units. But by requiringprecisely arranging the single boards in a rigid stacked arrangement inthe housing, by providing the exact interconnections between the boards,and by providing shock-absorbing components the prior art stack systemrequires an expensive and time-consuming manufacturing and assemblyprocess. As a consequence, overall cost of such prior art systems tendsto be high.

[0007] U.S. Pat. Nos. 3,904,934 and 3,529,213 disclose examples of thoseprior art card stack systems.

[0008] In view of the above there is a need for a card stack system thatcorrects the problems of the prior art card stack systems.

SUMMARY OF THE INVENTION

[0009] It is, therefore, object of the present invention to provide amethod to package and assemble electronic units having amulti-planar-board system without the disadvantages of prior artsystems.

[0010] It is another object of the present invention to provide ascalable housing for those electronic units.

[0011] These objects have been solved by the features of the independentclaims. Further advantageous embodiments of the present invention arelaid down in the dependent claims.

[0012] The present invention discloses method for packaging and assemblyof electronic units comprising a multi-planar board system in which eachsingle planar board provides electrical contacts and/or signal drive toits successive planar board via a flexible cable forming the onlyconnection between successive planar boards. In its packaged positionthe planar boards are laid upon one another without affixing them witheach other or affixing them with the housing of the electronic unit,wherein the packaging of the planar boards preferably forming a daisychain. Positioning and adjusting of the planar boards to each other ismainly achieved by the cover element being wrapped around all surfacesof the planar boards during the packaging process, positioning andclamping of the packaging of the planar boards within the housing ismainly achieved by the self-adapting suspension during the assemblyprocess of the electronic unit into the housing. The cover elementseparating and concurrently adjusting each planar boards to each otherhas isolating, stabilizing, heat draining, electromagnetic shielding andflexible attributes. The electronic unit is preferably arranged in ascrew-less, and scalable housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other objects, features and advantages will occur from thefollowing description of the preferred embodiments and the accompanyingdrawings wherein:

[0014]FIG. 1 shows the inventive flexible interconnections between thesingle planar boards of the multi-planar boards system of the electronicunit according to the present invention.

[0015]FIG. 2 shows a preferred embodiment of the arrangement of planarboards in a packaged position according to the present invention.

[0016]FIG. 3 shows a preferred embodiment of the cover element used bythe present invention.

[0017]FIG. 4 shows the preferred method for packaging of electronicunits according to the present invention.

[0018]FIG. 5 shows the final package of the electronic unit.

[0019]FIG. 6 shows the package of FIG. 5 arranged in a preferredembodiment of a housing.

[0020]FIG. 7 shows the housing of FIG. 6 with its inter-lockingstructure.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

[0021]FIG. 1 shows a multi-planar board system with four boards 1-4 in anon-packaged position. The basic system functions as well as thepotential system expansions are subdivided into four single planarboards 1-4. Each single extendible planar board 1 to 3 is at leastproviding the electrical contacts and signal drive supporting to extendthe multi-planar system with a successive planar board. That means thedrive capability as well as the signal distribution connectors are builtup consequently when adding on a consecutive planar board. Each singleextendible planar board 1-3 comprises a system specific entry connectoron one side and a pass-on connector on another side. Another likelyconfiguration is to have entry and pass-on connectors on one side ofeach planar board. Interconnections 12, 23, 34 between the single planarboards 1-4 are flexible cables. Advantageous the flexible cable can bebuilt by a planar inner plane stub allowing to be connected to the nextextender card at the end. Depending on the specific system to beimplemented the connectivity can be provided utilizing small connectorclamps or flexible cable may be simply soldered at the planars. The useof flexible cables (12, 23, 34) allows the entire arrangement of thesingle boards to be folded in a zigzag configuration, somewhat analogousto a concertina.

[0022]FIG. 2 shows a preferred embodiment of the arrangement of planarboards in a packaged position (cover element is not shown). The singleplanar boards 1-4 are arranged to each other in a so called “daisychain”. That means the single planar boards 1-4 are laid upon anotherwithout affixing them with each other or affixing them with the housingbeing used by the present invention. Positioning of the planar boards toeach other is mainly achieved by the cover element being wrapped aroundall surfaces of the planar boards during the packaging process,positioning and clamping of the package of the planar boards within thehousing is mainly achieved by the self-adapting suspension being part ofthe housing (not shown) during the assembly process. The onlyconnections between the planar boards are the flexible cables (12, 23,34). The use of flexible cables (12, 23, 34) allows the entire packagingof the planar boards to be folded in a zigzag manor concertina. Inanother embodiment of the present invention the flexible cables may bearranged at the same sides of the planar boards connecting one planarboard with another one. Preferably the electronic components of theopposite planar boards should be selected and arranged to each other tominimize to over-all height of the arrangement.

[0023]FIG. 3 shows a specific embodiment of the inventive cover element20 separating the planar boards from each other. In this embodiment thecover element is a heat pillow 20. The heat pillow 20 may be implementedas flexible plastic bag featuring stabilizing elements 32 and foldingpoints 27. The plastic bag may be filled with heat conducting liquid 25.Depending on the electronics system requirements, if necessary, theplastic bag may in addition incorporate a electromagnetic shielding foilor may be filled with liquid featuring shielding attributes. Thethickness may be defined taking the size and shape of the planar boardsand utilized electronic components into account. The heat conductingliquid could be simply water and if required complemented by antifreezeadd-ons. However, if advanced heat conducting characteristics andmechanical stabilization qualities are required, the bag may be filledapplying specific liquids featuring lower flowing attributes. Analternative to heat conducting liquids 25 is a gel especially a silicongel. The silicon gel is assembled mixing two base substances allowingthe gel to be adjusted to the desired attributes. Furthermore, any othermaterial with or without heat conducting liquids may be used when thattype of material fulfills following requirements:

[0024] 1) the material must support mounting and positioning of theplanar boards to each other

[0025] 2) isolating the electrical parts and planar boards from eachother

[0026] 3) minimizing acceleration forces effecting bigger/higher masselectrical components

[0027] 4) stabilizing the entire assembly keeping shock and vibrationstress at a minimum

[0028] 5) draining the dissipated heat energy from the electroniccomponents

[0029] 6) electromagnetic shielding of planar boards

[0030]FIG. 4 shows the preferred method for packaging of electronicunits by using the heat pillow of FIG. 3.

[0031] A first planar board 1 is placed onto a first part 30 of a coverelement 20. In the first step the second part 40 of the cover element 20is folded at its folding point 35 and placed at the surface of firstplanar board 1. In the second step the second planar board 2 is placedupon the first planar board 1 separated by the second part 40 of thecover element 20. In the third step the third part 50 of cover element20 is folded at its next folding point 45 and placed at the secondplanar board 2. In the fourth step the third planar board 3 is placed atthe second planar board 2 separated by the third part 50 of the coverelement 20. In fifth step the fourth part 60 of the cover element 20 isfolded at its folding point 55 and placed at the surface of the thirdplanar board 3. In a sixth step the fourth planar board 4 is placed atthe third planar board 3 separated by the fourth part 60 of the coverelement 20. In a preferred embodiment of the present invention thelongitudinal axis of said cover element (20) in its non-folded positionand the longitudinal axis of multi-planar board in its non-packagedposition are 90 rotated against each other when starting packaging ofsaid planar boards.

[0032] All these steps may be easily accomplished by an automaticassembly processes since no screws or other fixing elements are requiredin order to assemble the planar boards with each other. Therefore, themanufacturing process as well as the assembly process can be simplifiedas much as possible by applying the present invention.

[0033]FIG. 5 shows the final packaging of the electronic unit. The coverelement 20 is folded around all contacts and surfaces of the planarboards 1-4 including their electronic components as described to FIG. 4.An essential advantage of that packaging is that the planar boards donot need to lined up in a rectangular/straight orientation—rather givenby the size and height of the electronic components. The planar boardswill be self-aligning to the best positioning angle thus utilizing theminimum amount of assembly space.

[0034]FIG. 6 shows the housing 70 for the final packaging of FIG. 5. Inits basic implementation the housing comprises a bottom shell 80 and atop shell 90. Furthermore, a self-adapting suspension 100 is preferablyarranged at the inner side wall of the bottom shell 80 as well as at theinner side of the top shell 90. Other suspensions or springs achievingthe same effect may be used also. When placing the packaging 1-4 of theelectronic unit into the housing 70 the self-adapting suspensions 100will automatically force the packaging in the right clamping positionwithin the housing 70 and concurrently adjust the planar boards 1-4 withthe right pressure against each other without using screws, spacers orother fixing elements. If required connectors to allow electricalsignals to enter and exit the package can be fabricated in the housing.

[0035]FIG. 7 shows a preferred embodiment of the housing 70 as shown inFIG. 6. The scalable housing 70 comprising a bottom shell 80 and a topshell 90. The outer part of the bottom shell as well as the inner partof the top shell comprise a zigzag-teeth structure 110 allowingself-interlocking of top shell 90 with the bottom shell 80. When the topshell 90 is locked in the self-adapting suspension has reached aclamping force allowing adjusting the electronic unit in the housing.The zigzag teeth-structure 110 allowing to adjust the size housingdimension to fit the customized multi-boards system without replacingthe bottom shell 80 or top shell 90. The zigzag-teeth structure 110 isone preferred embodiment of the present invention. Other embodimentshaving the same technical effects may be used also.

[0036] Summarizing, the present invention includes, among other things,the following components:

[0037] a scalable housing allowing to adjust the size of the housing todifferent sizes of electronic units,

[0038] a mounting, adjusting, and cooling cover element used tophysically align and stabilize the planar boards and concurrently usedto transport the dissipated energy to the system housing components,

[0039] a suspension arranged in the bottom and top shell of the housingto position and stabilize the package of the planar boards in thehousing.

[0040] The main advantages of the present inventions are:

[0041] robust system attributes allowing shock resistant and vibrationresistant system implementations,

[0042] high system reliability due to robust packaging method. Heaviercomponents placed on planar boards do not require specific mountingreinforcement,

[0043] advantageous thermal behavior and minimized cooling effort,

[0044] significant cost advantage due to:

[0045] reduced system assembly components (“screw-less” system mount)basic system cooling provided by packaging method fast system assembly(manufacturing) time,

[0046] scalable system provided at a minimum base systemscale-infrastructure hardware overhead and a minimum overhead onphysical size and mass—easy system upgradability (“screw-less” systemmount and flexible housing),

[0047] reduced physical measures (size and weight),

[0048] ease of maintenance and repair efforts.

[0049] The invention may be preferably used for handheld devices (e.g.mobile phones), set-top systems, internet appliances, PCs as well as toembedded electronic devices requiring mechanical robustness and beingused in rugged environmental conditions such as e.g. demanded byelectronic devices used in industrial machinery tools and automotiveelectronic units.

1. A method to package electrical units comprising the acts of:providing a plurality of planar electronic circuit boards; providing acover element with defined folding points therein; connecting theplurality of planar electronic circuit boards with an electricalconductive member; placing a first planar electronic circuit board withits bottom side at a first part of said cover element; folding saidcover element at a defined folding point and placing a remaining part ofsaid cover element upon the surface of the top side of said first planarboard thereby covering the side surface of the first planar board;placing a second planar board with its bottom side at said surface ofthe remaining part of said cover element; folding said remaining coverelement at a further defined point and placing the newly remaining coverelement upon the surface of the top side of said second planar boardthereby covering the side surface of said second planar board; andrepeating the placing and folding steps until all surfaces of saidplanar electronic circuit boards are covered by said cover element. 2.The method according to claim 1, wherein each of said planar electroniccircuit boards includes a system specific entry connector at one sideand a pass-on connector at the other side.
 3. Packaging according toclaim 1, wherein each of said planar electronic circuit boards includesa system specific entry connector and a pass-on connector at one side.4. Packaging according to claim 2, wherein final packaging of saidplanar electronic circuit boards form a “daisy chain” configuration. 5.Packaging according to claim 1, wherein said cover element (20) is aplastic bag having stabilizing elements and folding points, wherein saidplastic bag is filled with a heat conducting liquid.
 6. Packagingaccording to claim 1, wherein said cover element (20) is a plastic baghaving stabilizing elements and folding points, wherein said plastic bagis filled with a liquid providing electromagnetic shielding attributes.7. Packaging according to claim 1, wherein said cover element (20) isfilled with a silicon gel.
 8. Packaging according to claim 1, whereinsaid cover element (20) forms a continuous element.
 9. Packagingaccording to claim 1, wherein the longitudinal axis of said coverelement (20) in its non-folded position and the longitudinal axis ofmulti-planar board in its non-packaged position are 90° rotated againsteach other when starting packaging of said planar boards.
 10. Packagingaccording to claim 1, wherein said packaging process is automaticallyaccomplished by a machine.
 11. A method to package electrical unitscomprising the acts of: providing a loosely connected multi-planarelectronic circuit board system including a plurality of single planarelectronic circuit boards connected to one another by flexible cablesand separated from one another by a continuous cover element; providinga housing having a lower shell section and an upper shell section;fitting said system of said planar boards into said bottom shell (80) ofsaid housing; positioning and clamping of said system in said bottomshell (80) by a self-adapting suspension (100) being part of the bottomshell (80); closing said housing with said top shell (90); positioningand clamping of said packaging against said top shell (90) by aself-adapting suspension (100) being part of the top shell when said topshell is self-interlocking with said bottom shell (80).
 12. Methodaccording to claim 11, wherein said self-interlocking between top (90)and bottom (80) shell is accomplished by a zigzag-teeth structure (110)being part of contacting surfaces of said bottom and top shell. 13.Method according to claim 11, wherein said assembly process isautomatically accomplished by a machine.
 14. Electronic unit comprising:a multi-planar board system, wherein said multi-planar board system ischaracterized by single planar boards (1-4) connected with each other bya flexible cable (12,23,34) providing electrical contacts and signaldrive, wherein the contacting surfaces of said planar boards areseparated from and adjusted to each other by a continuous cover element(20).
 15. Electronic unit according to claim 14, wherein saidmulti-planar board comprising single planar boards having a systemspecific entry connector at one side and a pass-on connector at theother side.
 16. Electronic unit according to claim 14, wherein saidmulti-planar board comprising single planar boards having a systemspecific entry connector and a pass-on connector at one side. 17.Electronic unit according to claim 14, wherein a final packaging of saidplanar boards builds up a “daisy chain” configuration.
 18. Electronicunit according to claim 14, wherein said cover element (20) includes aplastic bag having stabilizing elements and folding points, wherein saidplastic bag is filled with a heat conducting liquid.
 19. Electronic unitaccording to claim 14, wherein said cover element (20) is filled with asilicon gel.
 20. Housing (70) for an electronic unit comprising: abottom shell (80) having at least one self-adapting suspension (100) foradjusting and clamping a package in said bottom shell (80) when saidpackage is fully located in said bottom shell (80); and a top shell (90)having at least one self-adapting suspension (100) for adjusting andclamping said package against said top shell (90) when said top shell(90) is interlocked with said bottom shell (80).
 21. Housing (70)according to claim 20, wherein contacting faces of said bottom shell(80) and top shell (90) comprises a zigzag-teeth structure (110)allowing automatic interlocking and adjusting the size of said housing.22. An electronic assembly comprising: a housing including a bottomshell; at least a first self-adapting suspension operatively mounted toan inner wall of said bottom shell; a top shell having surfaces thatcoact with surfaces on the bottom shell to interlock the top shell tothe bottom shell; and at least a second self-adapting suspensionoperatively mounted to an inner wall of said top shell.
 23. Packagingaccording to claim 1 wherein said cover element is filled with shieldingfoil.
 24. The method of claim 1 wherein the electrical conductive memberincludes flexible cables.
 25. The electronic unit of claim 14 whereinsaid cover element is filled with a material having isolating,stabilizing, heat draining, foldable and flexible attributes.
 26. Theelectronic assembly of claim 22 wherein the self-adapting suspensionincludes springs.
 27. The electronic assembly of claim 22 or claim 26wherein the coacting surfaces include a structure that adjusts andinterlocks the top shell and bottom shell relative to each other. 28.The electronic assembly of claim 27 wherein the structure includeszigzag-teeth.
 29. The electronic assembly of claim 22 further includinga package of loosely connected planar electronic circuit boards placedin said housing and coacting with the self-adapting suspensions toadjust the position of said package within said housing.
 30. A method topackage electrical units comprising the acts of: providing a pluralityof planar electronic circuit boards; providing a cover element;connecting the plurality of planar electronic circuit boards with anelectrical conductive member; placing a first planar electronic circuitboard with its bottom side at a first part of said cover element;folding said cover element and placing a remaining part of said coverelement upon the surface of the top side of said first planar boardthereby covering the side surface of the first planar board; placing asecond planar board with its bottom side at said surface of theremaining part of said cover element; folding said remaining coverelement and placing the newly remaining cover element upon the surfaceof the top side of said second planar board thereby covering the sidesurface of said second planar board; and repeating the placing andfolding steps until all surfaces of said planar electronic circuitboards are covered by said cover element.